Sleep disorders are becoming increasingly prevalent in our society. It is estimated that 40 million Americans suffer from various sleep disorders. Further, 25 million more Americans suffer from intermittent-sleep-related disorders. Sleep disorders have various etiologies including stress induced by environmental and life style factors, physical factors, such as disease or obesity, and psychiatric disorders, such as depression.
Sleep disorders encompass, among other things, snoring, sleep apnea, insomnia, narcolepsy, restless legs syndrome, sleep terrors, sleep walking and sleep eating. Possible treatment can be as simple as behavior modification or it can be as involved as mechanical, surgical, or pharmacological intervention.
A particularly insidious sleep disorder is insomnia. Insomnia is defined as either having a difficulty falling asleep or overly frequent night awakenings. Insomnia can be caused by a number of different things including a change in environment, daily stress, caffeine, and other stimulants.
If left untreated, insomnia can adversely affect the quality of one's life. People with insomnia tend to suffer more frequently from depression and anxiety. Insomnia can also leave one tired and unable to perform at the workplace and/or even carry out normal daily activities. This inability to perform these activities has a negative impact on both professional and family life.
Typically, insomnia can be treated pharmacologically. Sedative hypnotics such as barbiturates, benzodiazepines and related compounds have been administered to treat insomnia. However, these compounds have a drawback because of the potential for addiction.
Sedating anti-histamine drugs have also been administered to treat insomnia. Agents such as diphenhydramine and hydroxyzine are typically administered due to their sedating properties. A second generation anti-histamine, ceterizine, is the primary acid metabolite of hydroxyzine resulting from the complete oxidation of hydroxyzine in vivo.
It has been reported that cetirizine may cause drowsiness when administered to patients. For instance, somnolence has been reported as the most frequently occurring side effect of cetirizine administration. Physician's Desk Reference, 2000 edition. Similarly, it has been reported that cetirizine impairs performance in tracking tests and increased both objective and subjective sleepiness in subjects. Nicholson AN, et al., Aviat. Space Environ. Med., 1998 Feb; 69(2): 166-71. Additionally, cetirizine has been reported to cause acute sedative activity by impairing driving performance and altering EEG energy spectra in the direction of electrocortical deactivation. Ramaeckers, et al., Eur. J. Clin. Pharmacol., 1992, 42: 363-369.
None of the aforementioned references discloses the use of cetirizine to treat sleep disorders, particularly insomnia. In fact, in all of these studies, cetirizine induced drowsiness was considered an unwanted side effect.